Heterogeneous photocatalysis has gained substantial research interest in treating per-and polyfluoroalkyl substances(PFAS)-contaminated water.However,sluggish degradation kinetics and low defluorination efficiency com...Heterogeneous photocatalysis has gained substantial research interest in treating per-and polyfluoroalkyl substances(PFAS)-contaminated water.However,sluggish degradation kinetics and low defluorination efficiency compromise their practical applications.Here,we report a superior photocatalyst,defected Bi_(3)O(OH)(PO_(4))_(2),which could effectively degrade typical PFAS,perfluorooctanoic acid(PFOA),with high defluorination efficiency.The UV light irradiation could in situ generate oxygen vacancies on Bi_(3)O(OH)(PO_(4))_(2) through oxidation of the lattice hydroxyls,which further promotes the formation of Lewis acidic coordinately unsaturated bismuth sites.Then,the Lewis acidic sites couple with the proximal surface hydroxyls to constitute the surface frustrated Lewis pairs(SFLPs).With the in-depth spectroscopic analysis,we revealed that the photo-induced SFLPs act as collection centers to effectively adsorb PFOA and endow accessible pathways to transfer photogenerated holes to PFOA rapidly.Consequently,activation of the terminal carboxyl,a ratelimiting step for PFOA decomposition,could be easily achieved over the defected Bi_(3)O(OH)(PO_(4))_(2) photocatalyst.These results suggest that SFLPs exhibit great potential in developing highly efficient photocatalysts to degrade persistent organic pollutants.展开更多
Benzimidazoles are very important chemical materials in the pharmaceutical industry,and the most common synthetic route is cyclization of o-phenylenediamine with carbon sources,in which utilization of inexpensive and ...Benzimidazoles are very important chemical materials in the pharmaceutical industry,and the most common synthetic route is cyclization of o-phenylenediamine with carbon sources,in which utilization of inexpensive and abundant CO_(2)as C1 source is very impressive.Porous aromatic frameworks(PAFs)with highly desired skeletons have attracted great attentions in gas capture and catalysis.Herein,B-based PAF-165 and PAF-166 are designed and synthesized via Friedel-Crafts alkylation reaction,which present high surface areas as well as high stability.Benefiting from the abundant electron-deficient B centers,both PAFs exhibit excellent selective CO_(2)adsorption abilities.The presence of sterically hindered B units in PAFs can act as Lewis acid active sites for the frustrated Lewis pairs(FLPs)in situ formation with ophenylenediamine,thus promoting the synthesis of benzimidazole.The optimal reaction conditions for o-phenylenediamine cyclization with PAF catalysts are explored,and the reaction mechanism is also proposed.This work provides feasible ideas for incorporating FLPs within porous materials as reusable heterogeneous catalysts for CO_(2)capture and conversion.展开更多
Sustainable CO_(2)fixation represents a facile and promising approach to constructing various valueadded chemicals.Herein,we contribute a robust metal-organic cage(MOC),denoted as TCPB-1,comprising a bulky Lewis acid ...Sustainable CO_(2)fixation represents a facile and promising approach to constructing various valueadded chemicals.Herein,we contribute a robust metal-organic cage(MOC),denoted as TCPB-1,comprising a bulky Lewis acid functionalized linker,which can in situ form frustrated Lewis pairs(FLPs)upon the addition of Lewis basic substrates to efficiently drive CO_(2)transformation.Significantly,the incorporation of Lewis acidic boron sites within TCPB-1 promotes the efficient CO_(2)conversion to potentially medicinal benzimidazole derivatives via an FLPmediated pathway,and boosts the stability/durability of the FLP catalyst.In addition,the underlying catalysis mechanism has been established by combined experimental and molecular simulation studies.This work not only advances FLP/MOC as a new type of highly efficient catalyst for CO_(2)chemical fixation,but also opens a new avenue to design heterogeneous FLP-based catalysts for small molecule activation and beyond.展开更多
In this study,a novel non-metallic carbon-based catalyst co-doped with boron and nitrogen(B,N)was successfully synthesized.By precisely controlling the carbonization temperature of a binary mixed ionic liquid,we selec...In this study,a novel non-metallic carbon-based catalyst co-doped with boron and nitrogen(B,N)was successfully synthesized.By precisely controlling the carbonization temperature of a binary mixed ionic liquid,we selectively modified the doping site structure,ultimately constructing a B,N co-doped frustrated Lewis acid-base pair catalyst.This catalyst exhibited remarkable catalytic activity,selectivity,and stability in the dehydrochlorination reaction of 1,1,2-trichloroethane(TCE).Detailed characterization and theoretical calculations revealed that the primary active center of this catalyst was the BN_(3)configuration.Compared to conventional graphitic N structures,the BN_(3)structure had a higher p-band center,ensuring superior adsorption and activation capabilities for TCE during the reaction.Within the BN_(3)site,three negatively charged nitrogen atoms acted as Lewis bases,while positively charged boron atoms acted as Lewis acids.This synergistic interaction facilitated the specific dissociation of chlorine and hydrogen atoms from TCE,significantly enhancing the 1,1-dichloroethene selectivity.Through this research,we not only explored the active site structure and catalytic mechanism of B,N co-doped catalysts in depth but also provided an efficient,selective,and stable catalyst for the dehydrochlorination of TCE,contributing significantly to the development of non-metallic catalysts.展开更多
Electrochemical NO_(2)~--to-NH_(3) conversion(NO_(2)RR) offers a green route to NH_(3) electrosynthesis, while developing efficient NO_(2)RR catalysis systems at high current densities remains a grand challenge. Herei...Electrochemical NO_(2)~--to-NH_(3) conversion(NO_(2)RR) offers a green route to NH_(3) electrosynthesis, while developing efficient NO_(2)RR catalysis systems at high current densities remains a grand challenge. Herein, we report an efficient Zr-NiO catalyst with atomically dispersed Zr-dopants incorporated in NiO lattice, delivering the exceptional NO_(2)RR performance with industriallevel current density(>0.2 A cm^(-2)). In situ spectroscopic measurements and theoretical simulations reveal the construction of ZrNi frustrated Lewis acid-base pairs(FLPs) on Zr-Ni O, which can substantially increase the number of absorbed nitrite(NO_(2)~-),promote the activation and protonation of NO_(2)~- and concurrently hamper the H coverage, boosting the activity and selectivity of Zr-NiO towards the NO_(2)RR. Remarkably, Zr-NiO exhibits the exceptional performance in a flow cell with high Faradaic efficiency for NH_(3) of 94.0% and NH_(3)yield rate of 1,394.1 μmol h^(-1)cm^(-2) at an industrial-level current density of 228.2 m A cm^(-2),placing it among the best NO_(2)RR electrocatalysts for NH_(3) production.展开更多
Comprehensive Summary,The asymmetric partial reduction of 1,3-diketones stands as a straightforward pathway to access optically active β-hydroxyketones. In this paper, an asymmetric Piers-type hydrosilylation of 2,2-...Comprehensive Summary,The asymmetric partial reduction of 1,3-diketones stands as a straightforward pathway to access optically active β-hydroxyketones. In this paper, an asymmetric Piers-type hydrosilylation of 2,2-difluoro-1,3-diketones was successfully realized by using a frustrated Lewis pair of chiral borane and tricyclohexylphosphine as a catalyst, delivering a variety of α,α-difluoro-β-hydroxyketones in high yields with up to 99% ee. Significantly, no over-reduced diol products were observed even with an excess amount of silanes. The product can be conveniently converted to α,α-difluoro-β-hydroxyester or 1,3-anti-diol via an oxidation with m-CPBA or a reduction with DIBAL-H without obvious loss of ee.展开更多
Single electron transition reactions between amines(Lewis base)and B(C_(6)F_(5))_(3)(Lewis acid)in cooperation with benzoquinones gave rise to a frustrated radical pair 3 and a nonfrustrated radical pair 4.Both of the...Single electron transition reactions between amines(Lewis base)and B(C_(6)F_(5))_(3)(Lewis acid)in cooperation with benzoquinones gave rise to a frustrated radical pair 3 and a nonfrustrated radical pair 4.Both of them were isolated as stable crystals and studied by single-crystal X-ray diffraction,superconducting quantum interference device measurements,electron paramagnetic resonance,nuclear magnetic resonance,and UV–vis spectroscopy.Antiferromagnetic exchange coupling was observed among both 3 and 4.Radical anion and cation are basically separated in 3,while 4 featured a relatively strong anion-cationπ–πstacking interaction.This work demonstrated that the Lewis acid coupled electron transfer is an efficient way to prepare stable radical ion pairs.展开更多
Lewis pair polymerization(LPP)has demonstrated its unique advantages,such as high activity,high stability,and adjustable variability,towards the polymerization of(meth)acrylate monomers in comparison with the other po...Lewis pair polymerization(LPP)has demonstrated its unique advantages,such as high activity,high stability,and adjustable variability,towards the polymerization of(meth)acrylate monomers in comparison with the other polymerization techniques.The combination of Lewis acid(LA)and Lewis base(LB)to construct Lewis pairs(LPs)with appropriate Lewis basicity,Lewis acidity,and steric effects would significantly impact the polymerization process,including chain initiation,propagation,termination and chain transfer reaction,as well as polymerization manner of monomers.In this feature article,we briefly review recent progress made by our research group towards the living/controlled polymerization of(meth)acrylate monomers,which were accomplished by a series of newly designed LPs,including monofunctional LPs,dual-initiating LPs and intramolecular tethered trifunctional LP.This article is divided into three parts:(1)the development of monofunctional living/controlled LP polymerization system;(2)the design and preparation of dual-initiating LPs in synthesizing thermoplastic elastomers;(3)the application of intramolecular trifunctional LP to the synthesis of cyclic polymers.These developed LPPs have demonstrated their powerful capability in precise control over the molecular weight,molecular weight distribution,and monomer sequence as well as the topology of polymers.This review will serve as a good resource or guideline for researchers currently working in the area of LPP and for those who are interested in synthesizing new materials by LPP.展开更多
The asymmetric hydrogenation of N-heteroarenes provides an efficient method for the synthesis of optically active cyclic secondary amines.In this paper,we described an asymmetric hydrogenation of phenanthridines using...The asymmetric hydrogenation of N-heteroarenes provides an efficient method for the synthesis of optically active cyclic secondary amines.In this paper,we described an asymmetric hydrogenation of phenanthridines using a chiral mono-alkene-derived borane.A variety of dihydrophenanthridines were furnished in high yields with up to 93%ee.The current catalytic system was very sensitive for the steric hindrance of phenanthridines.Bulky substituents at one phenyl group of phenanthridines were required to obtain the high enantioselectivity.But large substituents on the carbon of the C=N bonds would diminish the reactivity sharply.展开更多
One-step conversion of methane and formaldehyde into ethanol is a 100% atom-efficient process for carbon resources utilization and environment protection but still faces eminent challenges due to the lacking of effici...One-step conversion of methane and formaldehyde into ethanol is a 100% atom-efficient process for carbon resources utilization and environment protection but still faces eminent challenges due to the lacking of efficient catalysts. Therefore, developing active and stable catalysts is crucial for the co-conversion of methane and formaldehyde. Herein, twelve kinds of “Single-Atom”-“Frustrated Lewis Pair”(SA-FLP)dual-active-site catalysts are designed for the direct conversion of methane and formaldehyde to ethanol based on density functional theory(DFT) calculations and microkinetic simulations. The results show that the SA-FLP dual active sites can simultaneously activate methane at the SA site and activate formaldehyde at the FLP site. Among the twelve designed SA-FLP catalysts, Fe1-FLP shows the best performance in the co-conversion of methane and formaldehyde to ethanol with the rate-determining barrier of 1.15 e V.Ethanol is proved as the main product with the turnover frequency of 1.32 × 10^(-4)s^(-1)at 573 K and 3 bar.This work provides a universal strategy to design dual active sites on metal oxide materials and offers new insights into the effective conversion of methane and formaldehyde to desired C_(2) chemicals.展开更多
Aromaticity,in general,can promote a given reaction by stabilizing a transition state or a product via a mobility ofπelectrons in a cyclic structure.Similarly,such a promotion could be also achieved by destabilizing ...Aromaticity,in general,can promote a given reaction by stabilizing a transition state or a product via a mobility ofπelectrons in a cyclic structure.Similarly,such a promotion could be also achieved by destabilizing an antiaromatic reactant.However,both aromaticity and transition states cannot be directly measured in experiment.Thus,computational chemistry has been becoming a key tool to understand the aromaticity-driven reaction mechanisms.In this review,we will analyze the relationship between aromaticity and reaction mechanism to highlight the importance of density functional theory calculations and present it according to an approach via either aromatizing a transition state/product or destabilizing a reactant by antiaromaticity.Specifically,we will start with a particularly challenging example of dinitrogen activation followed by other small-molecule activation,Csingle bondF bond activation,rearrangement,as well as metathesis reactions.In addition,antiaromaticity-promoted dihydrogen activation,CO_(2)capture,and oxygen reduction reactions will be also briefly discussed.Finally,caution must be cast as the magnitude of the aromaticity in the transition states is not particularly high in most cases.Thus,a proof of an adequate electron delocalization rather than a complete ring current is recommended to support the relatively weak aromaticity in these transition states.展开更多
Frustrated Lewis pairs(FLPs) emerge as a new type of bifunctional metal-free catalysts for reversible H_2 activation, which is important for the storage and liberation of H_2 or further controllable utilizing chemic...Frustrated Lewis pairs(FLPs) emerge as a new type of bifunctional metal-free catalysts for reversible H_2 activation, which is important for the storage and liberation of H_2 or further controllable utilizing chemical fuels via hydrogenation/dehydrogenation. Herein, a DFT study was conducted to understand the geometric factors and electronic effects of FLPs on reversible H_2 activation. The Lewis base group mainly contributes to the proton attachment, and influences the kinetics of the H_2 activation. The Lewis acid group mainly relates to the hydride attachment, and affects more significantly on the thermodynamics of H_2 activation. The dimer and quenched structure of FLPs also have a degree of influence on the performance of catalyzed H_2 activation. A series of FLPs with para-substituted phenyl derivatives as LA groups were designed and evaluated. The results indicate that the variation of LA groups has significant impact on thermodynamic energy of dihydrogen adducts but insignificant effect on kinetics. Moreover,we found the thermodynamic energy of products has a good linear relationship with Hammett substituent constants. The solvent effect on H_2 activation was also studied, and polar solvent is beneficial for zwitterionic products. These results should provide deeper insight to understand the relation between FLPs structure and reactivity, which is critical for rational design of more efficient FLPs catalysts for reversible H_2 activation.展开更多
Main observation and conclusion In this work,a novel mode for the activation of N-heterocyclic carbene boranes(NHC-boranes)was developed by generating the highly reactive zwitterion species through hydride abstraction...Main observation and conclusion In this work,a novel mode for the activation of N-heterocyclic carbene boranes(NHC-boranes)was developed by generating the highly reactive zwitterion species through hydride abstraction with Lewis acid B(C_(6)F_(5))_(3) in an frustrated Lewis pairs manner.A broad range of alkenes including stilbenes,β-methylstyrenes,styrenes,and alkyl-alkenes were suitable substrates for the B(C_(6)F_(5))_(3)-catalyzed hydroboration to furnish the desired products in good to high yields.Significantly,excellent regioselectivities were obtained in some cases.Mechanistic studies indicate that the B-H bond cleavage is likely involved in the rate-determining step.In addition,an electrophilic addition of NHC-borenium cation to alkenes and the subsequent formation of carbocation are also postulated.The current work provides a promising method for the activation of stable borane adducts,which might lead to some interesting transformations in the future.展开更多
Olefins are very easily accessible compounds which are both popular substrates in synthetic chemistry and good ligands in the organometallic complexes.This dual character makes olefins a rich source of chiral ligands ...Olefins are very easily accessible compounds which are both popular substrates in synthetic chemistry and good ligands in the organometallic complexes.This dual character makes olefins a rich source of chiral ligands and catalysts for asymmetric catalysis.Herein,we willbriefly summarize our studies on the development of chiral diene ligands for transition-metal catalyzed asymmetric reactions and chiral FLP catalysts for asymmetric metal-free hydrogenations and hydrosilylations.Several acyclic chiral diene ligands as well as P/olefin and S/olefin hybrid ligands were developed for Rh or Pd-catalyzed asymmetric reactions.With these ligands in hand,we further put forward a novel strategy for acquiring chiral FLP catalysts via the in situ hydroboration of chiral dienes with Piers'borane.These catalysts proved to be highly ffective for asymmetric metal-free hydrogenations and hydrosilylations of imines,ilyl enol ethers,ketones,and aromatic N-heterocycles.展开更多
基金financially supported by the National Natural Science Foundation of China(Nos.22006088 and 42077293)the Natural Science Foundation of Guangdong Province(China)(No.2019QN01L797)+1 种基金the Shenzhen Municipal Science and Technology Innovation Committee(China)(Nos.WDZC20200817103015002 and RCYX20210609104448111)the Tsinghua Shenzhen International Graduate School(China)(Nos.HW2020002 and QD2021010N).
文摘Heterogeneous photocatalysis has gained substantial research interest in treating per-and polyfluoroalkyl substances(PFAS)-contaminated water.However,sluggish degradation kinetics and low defluorination efficiency compromise their practical applications.Here,we report a superior photocatalyst,defected Bi_(3)O(OH)(PO_(4))_(2),which could effectively degrade typical PFAS,perfluorooctanoic acid(PFOA),with high defluorination efficiency.The UV light irradiation could in situ generate oxygen vacancies on Bi_(3)O(OH)(PO_(4))_(2) through oxidation of the lattice hydroxyls,which further promotes the formation of Lewis acidic coordinately unsaturated bismuth sites.Then,the Lewis acidic sites couple with the proximal surface hydroxyls to constitute the surface frustrated Lewis pairs(SFLPs).With the in-depth spectroscopic analysis,we revealed that the photo-induced SFLPs act as collection centers to effectively adsorb PFOA and endow accessible pathways to transfer photogenerated holes to PFOA rapidly.Consequently,activation of the terminal carboxyl,a ratelimiting step for PFOA decomposition,could be easily achieved over the defected Bi_(3)O(OH)(PO_(4))_(2) photocatalyst.These results suggest that SFLPs exhibit great potential in developing highly efficient photocatalysts to degrade persistent organic pollutants.
基金the financial support by the Fundamental Research Funds for the Central Universities(No.2412019FZ008)the National Natural Science Foundation of China(Nos.22131004 and U21A20330)the"111 Project(No.B18012)。
文摘Benzimidazoles are very important chemical materials in the pharmaceutical industry,and the most common synthetic route is cyclization of o-phenylenediamine with carbon sources,in which utilization of inexpensive and abundant CO_(2)as C1 source is very impressive.Porous aromatic frameworks(PAFs)with highly desired skeletons have attracted great attentions in gas capture and catalysis.Herein,B-based PAF-165 and PAF-166 are designed and synthesized via Friedel-Crafts alkylation reaction,which present high surface areas as well as high stability.Benefiting from the abundant electron-deficient B centers,both PAFs exhibit excellent selective CO_(2)adsorption abilities.The presence of sterically hindered B units in PAFs can act as Lewis acid active sites for the frustrated Lewis pairs(FLPs)in situ formation with ophenylenediamine,thus promoting the synthesis of benzimidazole.The optimal reaction conditions for o-phenylenediamine cyclization with PAF catalysts are explored,and the reaction mechanism is also proposed.This work provides feasible ideas for incorporating FLPs within porous materials as reusable heterogeneous catalysts for CO_(2)capture and conversion.
基金supported by the Robert A.Welch Foundation(B-0027)H.R.thanks the University UNT as well as the CASCaM facility for their computing resources.Partial support from DOE/EERE(DE-EE0009418)(S.M.),NSFC(22001271)(C.-X.C.)Researchers Supporting Program(RSP2023R79)at King Saud University,Riyadh,Saudi Arabia(A.N.)is also acknowledged.
文摘Sustainable CO_(2)fixation represents a facile and promising approach to constructing various valueadded chemicals.Herein,we contribute a robust metal-organic cage(MOC),denoted as TCPB-1,comprising a bulky Lewis acid functionalized linker,which can in situ form frustrated Lewis pairs(FLPs)upon the addition of Lewis basic substrates to efficiently drive CO_(2)transformation.Significantly,the incorporation of Lewis acidic boron sites within TCPB-1 promotes the efficient CO_(2)conversion to potentially medicinal benzimidazole derivatives via an FLPmediated pathway,and boosts the stability/durability of the FLP catalyst.In addition,the underlying catalysis mechanism has been established by combined experimental and molecular simulation studies.This work not only advances FLP/MOC as a new type of highly efficient catalyst for CO_(2)chemical fixation,but also opens a new avenue to design heterogeneous FLP-based catalysts for small molecule activation and beyond.
基金the funding support from the National Natural Science Foundation of China(Nos.22202036 and 22302001)the Jilin Province Scientific,the Technological Planning Project of China(No.20230101292JC).
文摘In this study,a novel non-metallic carbon-based catalyst co-doped with boron and nitrogen(B,N)was successfully synthesized.By precisely controlling the carbonization temperature of a binary mixed ionic liquid,we selectively modified the doping site structure,ultimately constructing a B,N co-doped frustrated Lewis acid-base pair catalyst.This catalyst exhibited remarkable catalytic activity,selectivity,and stability in the dehydrochlorination reaction of 1,1,2-trichloroethane(TCE).Detailed characterization and theoretical calculations revealed that the primary active center of this catalyst was the BN_(3)configuration.Compared to conventional graphitic N structures,the BN_(3)structure had a higher p-band center,ensuring superior adsorption and activation capabilities for TCE during the reaction.Within the BN_(3)site,three negatively charged nitrogen atoms acted as Lewis bases,while positively charged boron atoms acted as Lewis acids.This synergistic interaction facilitated the specific dissociation of chlorine and hydrogen atoms from TCE,significantly enhancing the 1,1-dichloroethene selectivity.Through this research,we not only explored the active site structure and catalytic mechanism of B,N co-doped catalysts in depth but also provided an efficient,selective,and stable catalyst for the dehydrochlorination of TCE,contributing significantly to the development of non-metallic catalysts.
基金supported by the National Natural Science Foundation of China (52161025)the Natural Science Foundation of Gansu Province (20JR10RA241)。
文摘Electrochemical NO_(2)~--to-NH_(3) conversion(NO_(2)RR) offers a green route to NH_(3) electrosynthesis, while developing efficient NO_(2)RR catalysis systems at high current densities remains a grand challenge. Herein, we report an efficient Zr-NiO catalyst with atomically dispersed Zr-dopants incorporated in NiO lattice, delivering the exceptional NO_(2)RR performance with industriallevel current density(>0.2 A cm^(-2)). In situ spectroscopic measurements and theoretical simulations reveal the construction of ZrNi frustrated Lewis acid-base pairs(FLPs) on Zr-Ni O, which can substantially increase the number of absorbed nitrite(NO_(2)~-),promote the activation and protonation of NO_(2)~- and concurrently hamper the H coverage, boosting the activity and selectivity of Zr-NiO towards the NO_(2)RR. Remarkably, Zr-NiO exhibits the exceptional performance in a flow cell with high Faradaic efficiency for NH_(3) of 94.0% and NH_(3)yield rate of 1,394.1 μmol h^(-1)cm^(-2) at an industrial-level current density of 228.2 m A cm^(-2),placing it among the best NO_(2)RR electrocatalysts for NH_(3) production.
基金the financial support from the National Natural Science Foundation of China(21825108 and 22331011).
文摘Comprehensive Summary,The asymmetric partial reduction of 1,3-diketones stands as a straightforward pathway to access optically active β-hydroxyketones. In this paper, an asymmetric Piers-type hydrosilylation of 2,2-difluoro-1,3-diketones was successfully realized by using a frustrated Lewis pair of chiral borane and tricyclohexylphosphine as a catalyst, delivering a variety of α,α-difluoro-β-hydroxyketones in high yields with up to 99% ee. Significantly, no over-reduced diol products were observed even with an excess amount of silanes. The product can be conveniently converted to α,α-difluoro-β-hydroxyester or 1,3-anti-diol via an oxidation with m-CPBA or a reduction with DIBAL-H without obvious loss of ee.
基金the National Key R&D Program of China(grant no.2018YFA0306004)the National Natural Science Foundation of China(grant no.21525102)for their financial support.
文摘Single electron transition reactions between amines(Lewis base)and B(C_(6)F_(5))_(3)(Lewis acid)in cooperation with benzoquinones gave rise to a frustrated radical pair 3 and a nonfrustrated radical pair 4.Both of them were isolated as stable crystals and studied by single-crystal X-ray diffraction,superconducting quantum interference device measurements,electron paramagnetic resonance,nuclear magnetic resonance,and UV–vis spectroscopy.Antiferromagnetic exchange coupling was observed among both 3 and 4.Radical anion and cation are basically separated in 3,while 4 featured a relatively strong anion-cationπ–πstacking interaction.This work demonstrated that the Lewis acid coupled electron transfer is an efficient way to prepare stable radical ion pairs.
基金supported by the National Natural Science Foundation of China(22225104,22071077,21871107,21975102)China Postdoctoral Science Foundation(2022TQ0115,2022M711297)。
文摘Lewis pair polymerization(LPP)has demonstrated its unique advantages,such as high activity,high stability,and adjustable variability,towards the polymerization of(meth)acrylate monomers in comparison with the other polymerization techniques.The combination of Lewis acid(LA)and Lewis base(LB)to construct Lewis pairs(LPs)with appropriate Lewis basicity,Lewis acidity,and steric effects would significantly impact the polymerization process,including chain initiation,propagation,termination and chain transfer reaction,as well as polymerization manner of monomers.In this feature article,we briefly review recent progress made by our research group towards the living/controlled polymerization of(meth)acrylate monomers,which were accomplished by a series of newly designed LPs,including monofunctional LPs,dual-initiating LPs and intramolecular tethered trifunctional LP.This article is divided into three parts:(1)the development of monofunctional living/controlled LP polymerization system;(2)the design and preparation of dual-initiating LPs in synthesizing thermoplastic elastomers;(3)the application of intramolecular trifunctional LP to the synthesis of cyclic polymers.These developed LPPs have demonstrated their powerful capability in precise control over the molecular weight,molecular weight distribution,and monomer sequence as well as the topology of polymers.This review will serve as a good resource or guideline for researchers currently working in the area of LPP and for those who are interested in synthesizing new materials by LPP.
基金financial support from the National Natural Science Foundation of China(21825108 and 22331011).
文摘The asymmetric hydrogenation of N-heteroarenes provides an efficient method for the synthesis of optically active cyclic secondary amines.In this paper,we described an asymmetric hydrogenation of phenanthridines using a chiral mono-alkene-derived borane.A variety of dihydrophenanthridines were furnished in high yields with up to 93%ee.The current catalytic system was very sensitive for the steric hindrance of phenanthridines.Bulky substituents at one phenyl group of phenanthridines were required to obtain the high enantioselectivity.But large substituents on the carbon of the C=N bonds would diminish the reactivity sharply.
基金supported by the National Natural Science Foundation of China (Nos.22078257, 22038011 and 22108213)the China Postdoctoral Science Foundation (No.2021M692548)+1 种基金the Joint Fund of the Yulin University and the Dalian National Laboratory for Clean Energy (YLU-DNL Fund No.2022001)the Young Talent Support Plan of Shaanxi Province。
文摘One-step conversion of methane and formaldehyde into ethanol is a 100% atom-efficient process for carbon resources utilization and environment protection but still faces eminent challenges due to the lacking of efficient catalysts. Therefore, developing active and stable catalysts is crucial for the co-conversion of methane and formaldehyde. Herein, twelve kinds of “Single-Atom”-“Frustrated Lewis Pair”(SA-FLP)dual-active-site catalysts are designed for the direct conversion of methane and formaldehyde to ethanol based on density functional theory(DFT) calculations and microkinetic simulations. The results show that the SA-FLP dual active sites can simultaneously activate methane at the SA site and activate formaldehyde at the FLP site. Among the twelve designed SA-FLP catalysts, Fe1-FLP shows the best performance in the co-conversion of methane and formaldehyde to ethanol with the rate-determining barrier of 1.15 e V.Ethanol is proved as the main product with the turnover frequency of 1.32 × 10^(-4)s^(-1)at 573 K and 3 bar.This work provides a universal strategy to design dual active sites on metal oxide materials and offers new insights into the effective conversion of methane and formaldehyde to desired C_(2) chemicals.
基金the National Natural Science Foundation of China(22073079,22025105 and 21873079)the Ministry of Education of China(H20200504)+2 种基金the Top-Notch Young Talents Program of China is gratefully acknowledgedM.S.thanks the Ministerio de Ciencia e Innovación of Spain(project PID2020-113711GB-I00)the Generalitat de Catalunya(project 2017SGR39).
文摘Aromaticity,in general,can promote a given reaction by stabilizing a transition state or a product via a mobility ofπelectrons in a cyclic structure.Similarly,such a promotion could be also achieved by destabilizing an antiaromatic reactant.However,both aromaticity and transition states cannot be directly measured in experiment.Thus,computational chemistry has been becoming a key tool to understand the aromaticity-driven reaction mechanisms.In this review,we will analyze the relationship between aromaticity and reaction mechanism to highlight the importance of density functional theory calculations and present it according to an approach via either aromatizing a transition state/product or destabilizing a reactant by antiaromaticity.Specifically,we will start with a particularly challenging example of dinitrogen activation followed by other small-molecule activation,Csingle bondF bond activation,rearrangement,as well as metathesis reactions.In addition,antiaromaticity-promoted dihydrogen activation,CO_(2)capture,and oxygen reduction reactions will be also briefly discussed.Finally,caution must be cast as the magnitude of the aromaticity in the transition states is not particularly high in most cases.Thus,a proof of an adequate electron delocalization rather than a complete ring current is recommended to support the relatively weak aromaticity in these transition states.
基金supported by the National Natural Science Foundation of China (Nos. 21502023 and 21473261)the Guangdong Natural Science Funds for Distinguished Young Scholar(No. 2015A030306027)+1 种基金the Guangdong Special Support Plan for High-Level Talent(No. 20153100042090537)supported in part by the high performance grid computing platform of Sun Yat-sen University, the Guangdong Province Key Laboratory of Computational Science, and Special Program for Applied Research on Super Computation of the NSFC-Guangdong Joint Fund (No. U1501501)
文摘Frustrated Lewis pairs(FLPs) emerge as a new type of bifunctional metal-free catalysts for reversible H_2 activation, which is important for the storage and liberation of H_2 or further controllable utilizing chemical fuels via hydrogenation/dehydrogenation. Herein, a DFT study was conducted to understand the geometric factors and electronic effects of FLPs on reversible H_2 activation. The Lewis base group mainly contributes to the proton attachment, and influences the kinetics of the H_2 activation. The Lewis acid group mainly relates to the hydride attachment, and affects more significantly on the thermodynamics of H_2 activation. The dimer and quenched structure of FLPs also have a degree of influence on the performance of catalyzed H_2 activation. A series of FLPs with para-substituted phenyl derivatives as LA groups were designed and evaluated. The results indicate that the variation of LA groups has significant impact on thermodynamic energy of dihydrogen adducts but insignificant effect on kinetics. Moreover,we found the thermodynamic energy of products has a good linear relationship with Hammett substituent constants. The solvent effect on H_2 activation was also studied, and polar solvent is beneficial for zwitterionic products. These results should provide deeper insight to understand the relation between FLPs structure and reactivity, which is critical for rational design of more efficient FLPs catalysts for reversible H_2 activation.
基金the financial support from the National Natural Science Foundation of China(Nos.21871269 and 21521002).
文摘Main observation and conclusion In this work,a novel mode for the activation of N-heterocyclic carbene boranes(NHC-boranes)was developed by generating the highly reactive zwitterion species through hydride abstraction with Lewis acid B(C_(6)F_(5))_(3) in an frustrated Lewis pairs manner.A broad range of alkenes including stilbenes,β-methylstyrenes,styrenes,and alkyl-alkenes were suitable substrates for the B(C_(6)F_(5))_(3)-catalyzed hydroboration to furnish the desired products in good to high yields.Significantly,excellent regioselectivities were obtained in some cases.Mechanistic studies indicate that the B-H bond cleavage is likely involved in the rate-determining step.In addition,an electrophilic addition of NHC-borenium cation to alkenes and the subsequent formation of carbocation are also postulated.The current work provides a promising method for the activation of stable borane adducts,which might lead to some interesting transformations in the future.
基金We are grateful for the financial support from the National Natural Science Foundation of China(21521002 and 21825108).
文摘Olefins are very easily accessible compounds which are both popular substrates in synthetic chemistry and good ligands in the organometallic complexes.This dual character makes olefins a rich source of chiral ligands and catalysts for asymmetric catalysis.Herein,we willbriefly summarize our studies on the development of chiral diene ligands for transition-metal catalyzed asymmetric reactions and chiral FLP catalysts for asymmetric metal-free hydrogenations and hydrosilylations.Several acyclic chiral diene ligands as well as P/olefin and S/olefin hybrid ligands were developed for Rh or Pd-catalyzed asymmetric reactions.With these ligands in hand,we further put forward a novel strategy for acquiring chiral FLP catalysts via the in situ hydroboration of chiral dienes with Piers'borane.These catalysts proved to be highly ffective for asymmetric metal-free hydrogenations and hydrosilylations of imines,ilyl enol ethers,ketones,and aromatic N-heterocycles.